I completed my Google Educator certification back in February! I learned quite a bit going through the process. I used the Google for Education training website to prepare. You have to pass exams on Gmail, Calendar, Docs Suite, Sites and then you can pick one add on test (I chose Chrome). Each exam costs $15 and the certification is good for one year.
Side note: It looks like the Google Educator Exams are unavailable from April 8th through June 28th while the programs are being updated.